Method for producing low-salt high-quality sodium carbonate by combined filtration

Abstract

A method for producing low-salt high-quality sodium carbonate by combined filtration. A sodium bicarbonate crystal slurry suspension taken out from a soda-making carbonizing tower is filtered by a rotary drum vacuum filter; crude sodium bicarbonate is obtained by first-washing and blotting of a filter cake. Slurry with a solid-liquid ratio of 50-70 V% is obtained by mixing the crude sodium bicarbonate with water; the slurry is filtered by a belt vacuum filter; the filter cake is treated by second and third washing, blotting, and separation to obtain semi-finished sodium bicarbonate; and high-quality sodium carbonate is prepared by processing and treatment. The water used for the first washing is a filtrate of the belt vacuum filter; in the water used for the washing in twice in the belt vacuum filter, the water used for the former filter cake washing is the filtrate for the later filter cake washing; fresh water is used for the third filter cake washing. The mother liquor equivalent filtered by the belt vacuum filter is reduced by more than one time, and is reduced to 4-5 m3 / t for a combined soda-making method; water used for washing is reduced; the balance of the mother liquor isensured; the product quality is increased (NaCl contained in sodium bicarbonate is less than 0.15%, and NaCl contained in sodium carbonate is up to 0.1%); and the method facilitates environment protection.

Description

technical field [0001] The invention belongs to the field of alkali metal carbonate production, and relates to processing technologies such as a product quality improvement process in a soda ash production process. Background technique [0002] Soda ash is a bulk chemical product and a basic industrial raw material. In order to meet the use requirements of various industries, the quality of the products is different. With the continuous development and improvement of the national economy and the level of various industries, higher requirements are put forward for the product quality of soda ash production, and the demand for high-quality soda ash is also increasing year by year. [0003] At present, various production methods of high-quality soda ash at home and abroad have different impacts on product quality, economic benefits and production processes on soda ash production itself. Its production technology route is basically to calcinate the intermediate product - heavy ...

AI Technical Summary

Problems solved by technology

[0007] The remaining problems of drum vacuum filtration are: ① cylindrical drum vacuum filter can only deliquify, wash and dehydrate within a limited circle

② It is impossible to collect the filtered mother liquor and washing liquid separately and wash the washing water multiple times (the washing water can only be used once), which limits the improvement of product quality, and the washing water equivalent is relatively large

③Cylinder structure, high material requirements, high manufacturing precision, difficult to enlarge, high investment in equipment

[0009] ①The sealing periphery of the machine is relatively long, and the relative vacuum consumption is relatively large

Practice has proved that the environment is harsh and the loss of ammonia is large, which affects the popularization and application

③Direct production of low-salt (NaCl) heavy alkali to high-quality soda ash in this machine will also cause expansion of the mother liquor in the production system to a certain extent

[0010] Therefore, the current industry uses the above-mentioned (or other) filtration equipment alone for production, especially for the production of low-salt soda ash, and there are still many disadvantages that affect the production of soda ash

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